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我已经尝试实现 Nguyen Widrow 算法（如下），它似乎运行正常，但我有一些后续问题：

  • 这看起来像一个正确的实现吗？

  • Nguyen Widrow 初始化是否适用于任何网络拓扑/大小？（即5层AutoEncoder）

  • Nguyen Widrow 初始化对任何输入范围都有效吗？（0/1、-1/+1 等）

  • Nguyen Widrow 初始化对任何激活函数都有效吗？（即 Logistic、Tanh、Linear）

下面的代码假设网络已经被随机化为 -1/+1 ：

        ' Calculate the number of hidden neurons
        Dim HiddenNeuronsCount As Integer = Me.TotalNeuronsCount - (Me.InputsCount - Me.OutputsCount)

        ' Calculate the Beta value for all hidden layers
        Dim Beta As Double = (0.7 * Math.Pow(HiddenNeuronsCount, (1.0 / Me.InputsCount)))

        ' Loop through each layer in neural network, skipping input layer
        For i As Integer = 1 To Layers.GetUpperBound(0)

            ' Loop through each neuron in layer
            For j As Integer = 0 To Layers(i).Neurons.GetUpperBound(0)

                Dim InputsNorm As Double = 0

                ' Loop through each weight in neuron inputs, add weight value to InputsNorm
                For k As Integer = 0 To Layers(i).Neurons(j).ConnectionWeights.GetUpperBound(0)
                    InputsNorm += Layers(i).Neurons(j).ConnectionWeights(k) * Layers(i).Neurons(j).ConnectionWeights(k)
                Next

                ' Add bias value to InputsNorm
                InputsNorm += Layers(i).Neurons(j).Bias * Layers(i).Neurons(j).Bias

                ' Finalize euclidean norm calculation
                InputsNorm = Math.Sqrt(InputsNorm)

                ' Loop through each weight in neuron inputs, scale the weight based on euclidean norm and beta
                For k As Integer = 0 To Layers(i).Neurons(j).ConnectionWeights.GetUpperBound(0)
                    Layers(i).Neurons(j).ConnectionWeights(k) = (Beta * Layers(i).Neurons(j).ConnectionWeights(k)) / InputsNorm
                Next

                ' Scale the bias based on euclidean norm and beta
                Layers(i).Neurons(j).Bias = (Beta * Layers(i).Neurons(j).Bias) / InputsNorm

            Next

        Next
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1 回答 1

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Nguyen & Widrow 在他们的论文中假设输入介于 -1 和 +1 之间。Nguyen Widrow 初始化对任何长度有限的激活函数都有效。同样在他们的论文中，他们只讨论了 2 层神经网络，不确定 5 层神经网络。

小号

于 2013-01-14T11:25:41.087 回答